In a nutshell Mike ,no.Invest a little more for a meter that will read duty cycle. I paid $30Cdn for my digital multimeter and I don't know if it will read duty cycle or not.There could be a lot of reasons your car is running too rich besides just the O2 sensor and it's a giant leap from reading a value on the meter to understanding how to use that information to adjust or repair your problem.I know because I'm as newbie about this as you and I'd be in the same boat . Give me a breaker point distributor and a Holley carb on a small block Ford and I can diagnose and repair it with a dwell-tach a timing light and a vacuum gauge , now I need to take the next step to understand how my FI/ electronic ignition works and how to properly diagnose it . One day I'll get there
hopefully.